Epitaxially grown AlN and its optical band gap

Yim, Woosoon; Stofko, E. J.; Zanzucchi, P. J.; Pánkové, J. I.; Ettenberg, M.; Gilbert, Sarah L.

doi:10.1063/1.1661876

Cited by 578 publications

(184 citation statements)

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“…In addition, AlN has a high Debye temperature, 1150 K, 27 which Brgoch et al 9 have shown to be a good indicator of high quantum yield of Ce 3+ in a phosphor host. Further advantages such as excellent thermal shock resistance 10 and large band gap, 6.2 eV, 11 increase the attractiveness of an AlN-based ceramic down-conversion material for LED based white light.…”

confidence: 99%

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

et al. 2016

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We introduce high thermal conductivity aluminum nitride (AlN) as a transparent ceramic host for Ce3+, a well-known active ion dopant. We show that the Ce:AlN ceramics have overlapping photoluminescent (PL) emission peaks that cover almost the entire visible range resulting in a white appearance under 375 nm excitation without the need for color mixing. The PL is due to a combination of intrinsic AlN defect complexes and Ce3+ electronic transitions. Importantly, the peak intensities can be tuned by varying the Ce concentration and processing parameters, causing different shades of white light without the need for multiple phosphors or light sources. The Commission Internationale de l’Eclairage coordinates calculated from the measured spectra confirm white light emission. In addition, we demonstrate the viability of laser driven white light emission by coupling the Ce:AlN to a readily available frequency tripled Nd-YAG laser emitting at 355 nm. The high thermal conductivity of these ceramic down-converters holds significant promise for producing higher power white light sources than those available today.

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confidence: 99%

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

et al. 2016

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“…(2), where the band gaps of Sc x Ga 1-x N films have been presented in Ref. 16 and the band gap of AlN have been known as 6.2 eV 13,42 . Therefore, a band alignment diagram can be constructed, as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Tsui¹,

Goff²,

Palgrave³

et al. 2016

J. Phys. D: Appl. Phys.

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The valence band offsets of Sc x Ga 1-x N/AlN heterojunction were measured by X-ray photoelectron spectroscopy (XPS) and were found to increase from 0.42 eV to 0.95 eV as the Sc content x increased from 0 to 0.15. The increase in valence band offset with increasing x is attributed to the corresponding increase in spontaneous polarisation of the wurtzite structure. The Sc x Ga 1-x N/AlN heterojunction is type I, similar to other III-nitride-based heterojunctions. The results also indicated that a type II staggered heterojunction, which can enhance spatial charge separation, could be formed if Sc x Ga 1-x N is grown on GaN.

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“…The HRTEM images of the AlN film and sapphire substrate in is also valid for the growth accompanied by the formation of an amorphous interlayer. The relationship has usually been observed for epitaxial growth of AlN on the sapphire substrate without the formation of any amorphous interlayer by using methods such as laser ablation of AlN target, 15) vapor-phase reaction of AlCl 3 with NH 3 , 16) and metalorganic chemical vapor deposition. 17) Vennéguès and Beaumont observed no amorphous interlayer in the nitridation of (0001) sapphire surface by NH 3 and also showed the orientation relationship.…”

Section: )5)mentioning

confidence: 99%

Transmission electron microscopy study of the nitridated sapphire under a mixed gas flow of nitrogen and methane

Jung¹

2012

J. Ceram. Soc. Japan

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Delta-alumina (¤-Al 2 O 3 ) nanopowders and c-plane sapphires (¡-Al 2 O 3 ) were nitridated under a mixed gas flow of nitrogen and methane. The ¤-Al 2 O 3 nanopowders began to be converted to aluminum nitride (AlN) at 1300°C with phase transformation to ¡-Al 2 O 3 but were not completely converted to AlN even after 10 h at 1600°C. The X-ray diffraction pattern and cross-sectional high-resolution transmission electron microscopy image of the nitridated sapphire showed the orientation relationship of AlN[0001]««Al 2 O 3 [0001] in the growth and the formation of an amorphous AlO x N y interlayer between the AlN layer and the sapphire substrate. This formation strongly supported the reaction mechanism in which Al 2 O 3 converts to AlN through solid-state intermediates in the carbothermal reduction and nitridation reaction.©2012 The Ceramic Society of Japan. All rights reserved.Key-words : Aluminum nitride, Alumina, Sapphire, Methane, Carbothermal reduction, TEM [Received May 22, 2012; Accepted July 12, 2012] The carbothermal reduction and nitridation (CRN) method has been used for the commercial preparation of aluminum nitride (AlN) powder from alumina (Al 2 O 3 ) powder under a flow of nitrogen (N 2 ).1) The conventional CRN reaction is expressed by the equation:Al 2 O 3 ðsÞ þ 3CðsÞ þ N 2 ðgÞ ! 2AlNðsÞ þ 3COðgÞ ð1ÞThe method involves the intimate mixing of Al 2 O 3 with carbon powder and the burning up the excess carbon. A previous study showed that gaseous carbon greatly reduces the nitridation temperature of Al 2 O 3 .2) Therefore, Al 2 O 3 powder may be converted to AlN by calcination under a mixed gas of N 2 and methane (CH 4 ) without being mixed with carbon powder because the thermal decomposition of CH 4 gives gaseous carbon.In this note, ¤-Al 2 O 3 nanopowders and sapphires (¡-Al 2 O 3 ) were nitridated under a mixed gas flow of N 2 and CH 4 to examine their conversion to AlN. The reaction system in this study is very similar to that in the CRN method except that Al 2 O 3 powder is not used without being mixed with carbon. To the best of our knowledge, this is the first report on the nitridation of sapphire by the CRN method using an N 2 gas. Most studies on the nitridation of the sapphire surface have been focused on improving the morphological and optical properties of GaN film by reduction of the lattice mismatch between GaN and the sapphire substrate. 3)5)One method to nitridate the sapphire surface prior to GaN growth is to chemically convert the substrate surface using ammonia (NH 3 ) and a nitrogen plasma as nitrogen sources.3)10)The Al 2 O 3 nanopowders (<50 nm, Sigma-Aldrich Co.) in an alumina boat were placed in an alumina tube with an inner diameter of 34 mm and calcined for 10 h under a mixed gas flow of N 2 and CH 4 (0.1 vol %) (hereafter, 0.1 vol % CH 4 /N 2 ) in the temperature range of 13001600°C. The sample was taken from the furnace after it had cooled to room temperature. The gas flow rate and ramping rate were 200 ml/min and 5°C/min, respectively. The c-plane sapphire was cleaned thr...

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Epitaxially grown AlN and its optical band gap

Cited by 578 publications

References 31 publications

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Transmission electron microscopy study of the nitridated sapphire under a mixed gas flow of nitrogen and methane

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Epitaxially grown AlN and its optical band gap

Cited by 578 publications

References 31 publications

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

Valence band offsets of ScxGa1−xN/AlN and ScxGa1−xN/GaN heterojunctions

Transmission electron microscopy study of the nitridated sapphire under a mixed gas flow of nitrogen and methane

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Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions